Selective catalyst reduction wit pox reactor for engine exhaust aftertreatment

Abstract

An exhaust stream aftertreatment system that selectively reduces NOx emissions during lean-burn operation of an internal combustion engine is provided. The apparatus includes a partial oxidation reactor having a fuel source, an ignition device, and various values. The partial oxidation reactor is disposed in the exhaust pipe of automobile between the engine and the threeway catalyst. A light-off catalyst is provided adjacent to the engine, upstream from the partial oxidation reactor. The three-way catalyst and the light-off catalyst are typical automotive catalysts having a substrate plated with a precious metal to facilitate the oxidation of hydrocarbons (HC) and carbon monoxide (CO) as well as the reduction of nitrogen monoxide and nitrogen dioxide (NOx). The partial oxidation reactor is adapted to operate while the internal combustion engine is producing high levels of NOx or while the engine is operating in a lean burn regime.

What is claimed is: 
     
       1. An aftertreatment system for treating exhaust gas in an exhaust stream from an internal combustion engine, said aftertreatment system comprising: a first catalyst disposed downstream from the internal combustion engine;   a second catalyst disposed downstream from said first catalyst; and   a partial oxidation reactor disposed between said first and second catalyst; said partial oxidation reactor produces hydrogen rich products from a partial oxidation reaction, wherein said partial oxidation reactor includes a valving system, said valving system includes an inlet valve and an exit valve, said inlet valve can be opened selectively to allow the exhaust gas to flow into said partial oxidation reactor, said exit valve is opened selectively to allow said hydrogen rich products to mix with the exhaust stream in the aftertreatment system .   
     
     
       2. The aftertreatment system as set forth in claim 1, wherein said partial oxidation reactor includes a fuel source connected thereto, said fuel from said fuel source and said exhaust gas that flows into said partial oxidation reactor through said inlet valve react in said partial oxidation reactor to produce said hydrogen rich products.